Unverified news reports have suggested he may have been diagnosed with a personality disorder and/or with Asperger syndrome, a mild form of autism (considered a developmental disorder rather than mental illness).

But at this point, any discussion of whether mental illness played a role in Mr. Lanza’s apparent decision to shoot and kill his mother before shooting and killing 26 people at Sandy Hook Elementary School is pure speculation.

That hasn’t stopped the discussion, though. And many Americans are pointing to America’s flawed mental health care system – in addition to its gun laws – as a prime area needing attention in the wake of the tragedy.

Such discussion, say psychiatrists and mental-health experts, may be beneficial if it actually leads to increased care and treatment, as well as better funding of treatment programs. But it also runs the risk of further stigmatizing mental illness or reducing civil liberties of the mentally ill, if people start to associate mental illness with violence.

“We need to be proactive, rather than reactive: How do we reach out to families in trouble, and how do they reach out to the mental-health system?” says Michael Fitzpatrick, executive director of the National Alliance on Mental Illness (NAMI), who believes having mental health care more integrated with the regular health-care system might remove some of the stigma of seeking treatment. “From emergency-room doctors to police to clergy to schools and universities, we all need to be part of that public discussion of how do we get the support and treatment people need to people early enough so we’re not dealing with things at the very end when tragic things happen.”

'I am Adam Lanza's mother'

Just a day after the shooting, when very few details were known about Lanza, blogger Liza Long published a piece about her own experience with a mentally ill son that quickly went viral. Titled “I am Adam Lanza’s mother,” her blog was an impassioned plea for more discussion of mental illness and for more options and support for families, like hers, that struggle with it.

Her post quickly earned accolades for her courage and honesty, as well as detractors, particularly from those who worried she was doing even more to link mental illness with violence in readers' minds – even though the vast majority of those with mental illness never become violent. In particular, numerous families dealing with autism have been quick to dispel any notion that autism (or Asperger’s) is linked with violence.

Oversimplifying “mental illness” – already an extremely broad category – as the problem means “you’re tarring these millions of young people within this category that does get stigmatized, and reduces their opportunities in life in a lot of ways,” says Robert Whitaker, a science writer and author of “Anatomy of an Epidemic: Magic Bullets, Psychiatric Drugs, and the Astonishing Rise of Mental Illness in America.” “Whenever this conversation happens, we need to ... remember that what we want to do well as a society is be a society that tolerates differences, helps people in distress, and calls on our better self and not on our fearful self.”

Links to mass shootings

But others – while emphasizing that most mentally ill people are not violent – also agree that mental illness, often untreated or undiagnosed, has been a factor in many high-profile shootings, including Columbine, Virginia Tech, and the Gabrielle Giffords incident in Tucson, Ariz.

In looking at recent mass killings, at least half were associated with serious mental illness, says E. Fuller Torrey, founder of the Treatment Advocacy Center in Arlington, Va. And while it’s not clear yet what was behind last week's rampage, or whether it was preventable, some of them – including the Tucson shooting and the Colorado one earlier this year – probably were preventable, given the warning signs, Dr. Torrey says.

Torrey is an advocate for, among other things, easier avenues for involuntary commitment.

“At this point,” he says, “we’re so bent up on civil liberties that the screen we’ve set up to pick up people who are potentially dangerous has huge holes in it, and almost everyone sifts through.” In most states, he adds, people scared about what a family member might do are told that person has to break a law first before any action can be taken.

But committing or treating someone involuntarily is a huge and often traumatic step, Mr. Whitaker notes. “If we’re a freedom-loving people, doing that sort of thing ought to give us pause.... Is there evidence that forced commitment reduces risk of violence? I don’t know.”

Moreover, he says, while he is a big advocate of helping people access treatment, there are also dangers that come with certain antipsychotic drugs that have been linked to homicidal thoughts in rare instances. And without careful monitoring, some drugs may actually lead to some episodes of violence. Lanza, according to some reports, was taking an antipsychotic associated with those side effects.

“There’s a knee-jerk response to get people in treatment and that will solve everything, but we have to ask, does treatment in any way pose a risk?” Whitaker says.

System under stress

One thing that most mental-health experts can agree on is the current system isn’t meeting the needs of many individuals.

About 39 percent of all people who have a diagnosis and are in need of treatment actually get treatment in a given year, says Mr. Fitzpatrick of NAMI. Since the economic challenges in 2009, he adds, $4.35 billion in state general funds has been cut from the mental-health system.

On the other hand, Fitzpatrick has hopes that the Affordable Care Act will help millions of Americans who currently have no coverage for mental-health services to get such coverage. “That’s a game-changer,” he says.

While little confirmed information is known yet about the role mental illness may have played in the Sandy Hook shooting, having a national conversation about it still makes sense simply based on the patterns from past shootings, says Christopher Ferguson, a professor of psychology and criminal justice at Texas A&M International University in Laredo.

Most past shooters, he says, have certain common traits: a history of antisocial traits or behaviors; some sort of mental-health problem, often psychosis or depression; and a characterization as “injustice collectors” who blame others for problems.

With a tragedy that has captured the national consciousness, Professor Ferguson says, “a big part of the focus has to be on mental health and the inadequacies of our mental-health system.” In the past, he says, people have been reluctant to have tax dollars go toward what they see as “welfare.” “We need to repackage [mental-health services] as less to do with welfare and more to do with public safety,” he says.

Like Torrey, he believes that increasing the ability to commit people who may pose a threat is one option that needs to be explored more – even while he still sees a risk of, essentially, incarcerating people for crimes they haven’t committed. It's key, he says, to have good assessments and to ensure that treatment facilities offer adequate and humane care.

Psychiatrists also emphasize the need, in looking at this case and others, to avoid confusing various forms of mental illness and developmental and personality disorders – and also to realize that there’s no firm line determining when someone is, or isn’t, mentally ill. Moreover, a “diagnosis” is often a somewhat arbitrary process that explains a variety of overlapping conditions.

“It’s very important to make distinctions between the psychotic and the psychopathic, but there can also be people who are neither, and who have developmental and personality disorders that could explain a failure to be empathetic and a failure to act in a lawful way, ” says Frank Ochberg, a clinical professor of psychiatry at Michigan State University in East Lansing and a former associate director of the National Institute of Mental Health. Psychopathic individuals, he says, are those lacking a conscience, while people with psychotic disorders have a hard time distinguishing what’s real for a period of time.

In Lanza’s case, while nothing is known yet, “in due course we may learn that he fit neither,” says Dr. Ochberg. “If we learn that, it will expand our thinking about young men who are potentially dangerous, even though they lack sadistic intent.”